The result of the experiment identifies that the color of the ovule parent prevails and assigns the color of the offspring. The female parental branches that were all-green or all-white had children of all-green or all-white, respectively. The female parental branches that were variegated resulted in all three types of offspring. Show It is evident that the chloroplast shows maternal (pollen plant) inheritance. The branch that is pure green will produce ovules with green chloroplasts that will give rise to an all-green offspring. Thus, an all-white branch will have offspring with ovules with an exclusive content of white chloroplasts and will give rise to a pure white offspring. If a branch is variegated, it is combined, some with only functional chloroplasts, some with only non-functional chloroplasts, and some with a mixture of chloroplasts. All three types of cells can give rise to ovules, leading to green offspring, white offspring, and variegated offspring. The response indicates that chloroplasts are transmitted to progeny only from the female parent in the ovule and that the progeny produced always match or can be produced from the ovule used in the cross. What causes trisomy 21 meiosis?Trisomy 21 (Nondisjunction)
Down syndrome is usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate.
Why is trisomy 21 the most common?Trisomy 21 (Down syndrome) is the most common autosomal trisomy in newborns, and is strongly associated with increasing maternal age. Trisomy 21 results most commonly from maternal meiotic nondisjunction. Unbalanced translocation accounts for up to 4% of cases.
What causes the most common chromosomal abnormality called trisomy 21 quizlet?Also known as Down syndrome, trisomy 21 is a genetic condition caused by an extra chromosome. Most babies inherit 23 chromosomes from each parent, for a total of 46 chromosomes. Babies with Down syndrome however, end up with three chromosomes at position 21, instead of the usual pair.
What is the source of the extra chromosome 21 in an individual with Down syndrome?To date, no behavioral activity of the parents or environmental factor is known to cause Down syndrome. After much research on these cell division errors, researchers know that: In the majority of cases, the extra copy of chromosome 21 comes from the mother in the egg.
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Which of the following is most likely the primary cause of the pattern of frequency of trisomy 21?
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